plugin: simplify hooks calling methods, and make lifetime requirements explicit.

They callback must take ownership of the payload (almost all do, but
now it's explicit).

And since the payload and cb_arg arguments to plugin_hook_call_() are
always identical, make them a single parameter.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

lightningd/invoice.c

@@ -231,7 +231,7 @@ static const u8 *hook_gives_failmsg(const tal_t *ctx,
 }
 
 static void
-invoice_payment_hook_cb(struct invoice_payment_hook_payload *payload,
+invoice_payment_hook_cb(struct invoice_payment_hook_payload *payload STEALS,
 			const char *buffer,
 			const jsmntok_t *toks)
 {
@@ -281,7 +281,6 @@ invoice_payment_hook_cb(struct invoice_payment_hook_payload *payload,
 REGISTER_PLUGIN_HOOK(invoice_payment,
 		     PLUGIN_HOOK_SINGLE,
 		     invoice_payment_hook_cb,
-		     struct invoice_payment_hook_payload *,
 		     invoice_payment_serialize,
 		     struct invoice_payment_hook_payload *);
 
@@ -360,7 +359,7 @@ void invoice_try_pay(struct lightningd *ld,
 {
 	struct invoice_payment_hook_payload *payload;
 
-	payload = tal(ld, struct invoice_payment_hook_payload);
+	payload = tal(NULL, struct invoice_payment_hook_payload);
 	payload->ld = ld;
 	payload->label = tal_steal(payload, details->label);
 	payload->msat = set->so_far;
@@ -368,7 +367,7 @@ void invoice_try_pay(struct lightningd *ld,
 	payload->set = set;
 	tal_add_destructor2(set, invoice_payload_remove_set, payload);
 
-	plugin_hook_call_invoice_payment(ld, payload, payload);
+	plugin_hook_call_invoice_payment(ld, payload);
 }
 
 static bool hsm_sign_b11(const u5 *u5bytes,

lightningd/jsonrpc.c

@@ -29,6 +29,7 @@
 #include <common/memleak.h>
 #include <common/param.h>
 #include <common/timeout.h>
+#include <common/utils.h>
 #include <common/version.h>
 #include <common/wireaddr.h>
 #include <errno.h>
@@ -676,13 +677,16 @@ fail:
 }
 
 static void
-rpc_command_hook_callback(struct rpc_command_hook_payload *p,
+rpc_command_hook_callback(struct rpc_command_hook_payload *p STEALS,
                           const char *buffer, const jsmntok_t *resulttok)
 {
 	const jsmntok_t *tok, *params, *custom_return;
 	const jsmntok_t *innerresulttok;
 	struct json_stream *response;
 
+	/* Free payload with cmd */
+	tal_steal(p->cmd, p);
+
 	params = json_get_member(p->buffer, p->request, "params");
 
 	/* If no plugin registered, just continue command execution. Same if
@@ -767,13 +771,12 @@ rpc_command_hook_callback(struct rpc_command_hook_payload *p,
 
 REGISTER_PLUGIN_HOOK(rpc_command, PLUGIN_HOOK_SINGLE,
 		     rpc_command_hook_callback,
-                     struct rpc_command_hook_payload *,
                      rpc_command_hook_serialize,
                      struct rpc_command_hook_payload *);
 
 static void call_rpc_command_hook(struct rpc_command_hook_payload *p)
 {
-	plugin_hook_call_rpc_command(p->cmd->ld, p, p);
+	plugin_hook_call_rpc_command(p->cmd->ld, p);
 }
 
 /* We return struct command_result so command_fail return value has a natural
@@ -842,7 +845,7 @@ parse_request(struct json_connection *jcon, const jsmntok_t tok[])
 				    jcon->buffer + method->start);
 	}
 
-	rpc_hook = tal(c, struct rpc_command_hook_payload);
+	rpc_hook = tal(NULL, struct rpc_command_hook_payload);
 	rpc_hook->cmd = c;
 	/* Duplicate since we might outlive the connection */
 	rpc_hook->buffer = tal_dup_talarr(rpc_hook, char, jcon->buffer);

lightningd/onion_message.c

@@ -41,7 +41,7 @@ onion_message_serialize(struct onion_message_hook_payload *payload,
 }
 
 static void
-onion_message_hook_cb(struct onion_message_hook_payload *payload,
+onion_message_hook_cb(struct onion_message_hook_payload *payload STEALS,
 			 const char *buffer,
 			 const jsmntok_t *toks)
 {
@@ -53,7 +53,6 @@ onion_message_hook_cb(struct onion_message_hook_payload *payload,
 REGISTER_PLUGIN_HOOK(onion_message,
 		     PLUGIN_HOOK_CHAIN,
 		     onion_message_hook_cb,
-		     struct onion_message_hook_payload *,
 		     onion_message_serialize,
 		     struct onion_message_hook_payload *);
 
@@ -112,7 +111,7 @@ void handle_onionmsg_to_us(struct channel *channel, const u8 *msg)
 	log_debug(channel->log, "Got onionmsg%s%s",
 		  payload->reply_blinding ? " reply_blinding": "",
 		  payload->reply_path ? " reply_path": "");
-	plugin_hook_call_onion_message(ld, payload, payload);
+	plugin_hook_call_onion_message(ld, payload);
 }
 
 void handle_onionmsg_forward(struct channel *channel, const u8 *msg)

lightningd/opening_control.c

@@ -754,7 +754,7 @@ static void openchannel_payload_remove_openingd(struct subd *openingd,
 	payload->openingd = NULL;
 }
 
-static void openchannel_hook_cb(struct openchannel_hook_payload *payload,
+static void openchannel_hook_cb(struct openchannel_hook_payload *payload STEALS,
 			    const char *buffer,
 			    const jsmntok_t *toks)
 {
@@ -829,7 +829,6 @@ static void openchannel_hook_cb(struct openchannel_hook_payload *payload,
 REGISTER_PLUGIN_HOOK(openchannel,
 		     PLUGIN_HOOK_SINGLE,
 		     openchannel_hook_cb,
-		     struct openchannel_hook_payload *,
 		     openchannel_hook_serialize,
 		     struct openchannel_hook_payload *);
 
@@ -847,7 +846,7 @@ static void opening_got_offer(struct subd *openingd,
 		return;
 	}
 
-	payload = tal(openingd->ld, struct openchannel_hook_payload);
+	payload = tal(openingd, struct openchannel_hook_payload);
 	payload->openingd = openingd;
 	if (!fromwire_opening_got_offer(payload, msg,
 					&payload->funding_satoshis,
@@ -868,7 +867,7 @@ static void opening_got_offer(struct subd *openingd,
 	}
 
 	tal_add_destructor2(openingd, openchannel_payload_remove_openingd, payload);
-	plugin_hook_call_openchannel(openingd->ld, payload, payload);
+	plugin_hook_call_openchannel(openingd->ld, payload);
 }
 
 static unsigned int openingd_msg(struct subd *openingd,

lightningd/peer_control.c

@@ -860,7 +860,7 @@ peer_connected_serialize(struct peer_connected_hook_payload *payload,
 }
 
 static void
-peer_connected_hook_cb(struct peer_connected_hook_payload *payload,
+peer_connected_hook_cb(struct peer_connected_hook_payload *payload STEALS,
 		       const char *buffer,
 		       const jsmntok_t *toks)
 {
@@ -974,7 +974,6 @@ send_error:
 
 REGISTER_PLUGIN_HOOK(peer_connected, PLUGIN_HOOK_SINGLE,
 		     peer_connected_hook_cb,
-		     struct peer_connected_hook_payload *,
 		     peer_connected_serialize,
 		     struct peer_connected_hook_payload *);
 
@@ -1018,7 +1017,7 @@ void peer_connected(struct lightningd *ld, const u8 *msg,
 	assert(!peer->uncommitted_channel);
 	hook_payload->channel = peer_active_channel(peer);
 
-	plugin_hook_call_peer_connected(ld, hook_payload, hook_payload);
+	plugin_hook_call_peer_connected(ld, hook_payload);
 }
 
 /* FIXME: Unify our watch code so we get notified by txout, instead, like
@@ -2297,7 +2296,7 @@ struct custommsg_payload {
 	const u8 *msg;
 };
 
-static void custommsg_callback(struct custommsg_payload *payload,
+static void custommsg_callback(struct custommsg_payload *payload STEALS,
 			       const char *buffer, const jsmntok_t *toks)
 {
 	tal_free(payload);
@@ -2310,8 +2309,9 @@ static void custommsg_payload_serialize(struct custommsg_payload *payload,
 	json_add_node_id(stream, "peer_id", &payload->peer_id);
 }
 
-REGISTER_PLUGIN_HOOK(custommsg, PLUGIN_HOOK_SINGLE, custommsg_callback,
-		     struct custommsg_payload *, custommsg_payload_serialize,
+REGISTER_PLUGIN_HOOK(custommsg, PLUGIN_HOOK_SINGLE,
+		     custommsg_callback,
+		     custommsg_payload_serialize,
 		     struct custommsg_payload *);
 
 void handle_custommsg_in(struct lightningd *ld, const struct node_id *peer_id,
@@ -2329,7 +2329,7 @@ void handle_custommsg_in(struct lightningd *ld, const struct node_id *peer_id,
 
 	p->peer_id = *peer_id;
 	p->msg = tal_steal(p, custommsg);
-	plugin_hook_call_custommsg(ld, p, p);
+	plugin_hook_call_custommsg(ld, p);
 }
 
 static struct command_result *json_sendcustommsg(struct command *cmd,

lightningd/peer_htlcs.c

@@ -976,7 +976,7 @@ static void htlc_accepted_hook_serialize(struct htlc_accepted_hook_payload *p,
  * Callback when a plugin answers to the htlc_accepted hook
  */
 static void
-htlc_accepted_hook_callback(struct htlc_accepted_hook_payload *request,
+htlc_accepted_hook_callback(struct htlc_accepted_hook_payload *request STEALS,
 			    const char *buffer, const jsmntok_t *toks)
 {
 	struct route_step *rs = request->route_step;
@@ -1027,7 +1027,6 @@ htlc_accepted_hook_callback(struct htlc_accepted_hook_payload *request,
 
 REGISTER_PLUGIN_HOOK(htlc_accepted, PLUGIN_HOOK_CHAIN,
 		     htlc_accepted_hook_callback,
-		     struct htlc_accepted_hook_payload *,
 		     htlc_accepted_hook_serialize,
 		     struct htlc_accepted_hook_payload *);
 
@@ -1160,7 +1159,7 @@ static bool peer_accepted_htlc(const tal_t *ctx,
 		goto fail;
 	}
 
-	hook_payload = tal(hin, struct htlc_accepted_hook_payload);
+	hook_payload = tal(NULL, struct htlc_accepted_hook_payload);
 
 	hook_payload->route_step = tal_steal(hook_payload, rs);
 	hook_payload->payload = onion_decode(hook_payload, rs,
@@ -1186,7 +1185,7 @@ static bool peer_accepted_htlc(const tal_t *ctx,
 #endif
 		hook_payload->next_blinding = NULL;
 
-	plugin_hook_call_htlc_accepted(ld, hook_payload, hook_payload);
+	plugin_hook_call_htlc_accepted(ld, hook_payload);
 
 	/* Falling through here is ok, after all the HTLC locked */
 	return true;

lightningd/plugin_hook.c

@@ -14,7 +14,6 @@ struct plugin_hook_request {
 	struct plugin *plugin;
 	const struct plugin_hook *hook;
 	void *cb_arg;
-	void *payload;
 	struct db *db;
 	struct lightningd *ld;
 };
@@ -221,13 +220,13 @@ static void plugin_hook_call_next(struct plugin_hook_request *ph_req)
 				    plugin_get_log(ph_req->plugin),
 				    plugin_hook_callback, ph_req);
 
-	hook->serialize_payload(ph_req->payload, req->stream);
+	hook->serialize_payload(ph_req->cb_arg, req->stream);
 	jsonrpc_request_end(req);
 	plugin_request_send(ph_req->plugin, req);
 }
 
 void plugin_hook_call_(struct lightningd *ld, const struct plugin_hook *hook,
-		       void *payload, void *cb_arg)
+		       tal_t *cb_arg STEALS)
 {
 	struct plugin_hook_request *ph_req;
 	struct plugin_hook_call_link *link;
@@ -239,9 +238,8 @@ void plugin_hook_call_(struct lightningd *ld, const struct plugin_hook *hook,
 		 * to eventually to inspect in-flight requests. */
 		ph_req = notleak(tal(hook->plugins, struct plugin_hook_request));
 		ph_req->hook = hook;
-		ph_req->cb_arg = cb_arg;
+		ph_req->cb_arg = tal_steal(ph_req, cb_arg);
 		ph_req->db = ld->wallet->db;
-		ph_req->payload = tal_steal(ph_req, payload);
 		ph_req->ld = ld;
 
 		list_head_init(&ph_req->call_chain);

lightningd/plugin_hook.h

@@ -28,13 +28,14 @@
  * delivery to the plugin, and from a JSON-object to the internal
  * representation:
  *
- * - `serialize_payload` which takes a payload of type `payload_type`
+ * - `serialize_payload` which takes a payload of type `cb_arg_type`
  *   and serializes it into the given `json_stream`. `
  *
  * - `response_cb` is called once the plugin has responded (or with
  *   buffer == NULL if there's no plugin).  In addition an arbitrary
  *   additional argument of type `cb_arg_type` can be passed along
- *   that may contain any additional context necessary.
+ *   that may contain any additional context necessary.  It must free
+ *   or otherwise take ownership of the cb_arg_type argument.
  *
  *
  * To make hook invocations easier, each hook registered with
@@ -69,7 +70,7 @@ AUTODATA_TYPE(hooks, struct plugin_hook);
  * wrappers generated by the `PLUGIN_HOOK_REGISTER` macro.
  */
 void plugin_hook_call_(struct lightningd *ld, const struct plugin_hook *hook,
-		       void *payload, void *cb_arg);
+		       tal_t *cb_arg STEALS);
 
 
 /* Create a small facade in from of `plugin_hook_call_` to make sure
@@ -78,13 +79,11 @@ void plugin_hook_call_(struct lightningd *ld, const struct plugin_hook *hook,
  * the method-name is correct for the call.
  */
 /* FIXME: Find a way to avoid back-to-back declaration and definition */
-#define PLUGIN_HOOK_CALL_DEF(name, payload_type, response_cb_arg_type)         \
+#define PLUGIN_HOOK_CALL_DEF(name, cb_arg_type)				       \
 	UNNEEDED static inline void plugin_hook_call_##name(                   \
-	    struct lightningd *ld, payload_type payload,                       \
-	    response_cb_arg_type cb_arg)                                       \
+	    struct lightningd *ld, cb_arg_type cb_arg STEALS)                  \
 	{                                                                      \
-		plugin_hook_call_(ld, &name##_hook_gen, (void *)payload,       \
-				  (void *)cb_arg);                             \
+		plugin_hook_call_(ld, &name##_hook_gen, cb_arg);               \
 	}
 
 /* Typechecked registration of a plugin hook. We check that the
@@ -95,23 +94,22 @@ void plugin_hook_call_(struct lightningd *ld, const struct plugin_hook *hook,
  * response_cb function accepts the deserialized response format and
  * an arbitrary extra argument used to maintain context.
  */
-#define REGISTER_PLUGIN_HOOK(name, type, response_cb, response_cb_arg_type,    \
-			     serialize_payload, payload_type)                  \
+#define REGISTER_PLUGIN_HOOK(name, type, response_cb,			       \
+			     serialize_payload, cb_arg_type)	               \
 	struct plugin_hook name##_hook_gen = {                                 \
 	    stringify(name),                                                   \
 	    type,                                                              \
 	    typesafe_cb_cast(                                                  \
-		void (*)(void *, const char *, const jsmntok_t *),             \
-		void (*)(response_cb_arg_type, const char *,                   \
-			 const jsmntok_t *),                                   \
+		void (*)(void *STEALS, const char *, const jsmntok_t *),       \
+		void (*)(cb_arg_type STEALS, const char *, const jsmntok_t *), \
 		response_cb),                                                  \
 	    typesafe_cb_cast(void (*)(void *, struct json_stream *),           \
-			     void (*)(payload_type, struct json_stream *),     \
+			     void (*)(cb_arg_type, struct json_stream *),      \
 			     serialize_payload),                               \
 	    NULL, /* .plugins */                                               \
 	};                                                                     \
 	AUTODATA(hooks, &name##_hook_gen);                                     \
-	PLUGIN_HOOK_CALL_DEF(name, payload_type, response_cb_arg_type);
+	PLUGIN_HOOK_CALL_DEF(name, cb_arg_type)
 
 bool plugin_hook_register(struct plugin *plugin, const char *method);
 

lightningd/test/run-invoice-select-inchan.c

@@ -375,7 +375,7 @@ void per_peer_state_set_fds(struct per_peer_state *pps UNNEEDED,
 { fprintf(stderr, "per_peer_state_set_fds called!\n"); abort(); }
 /* Generated stub for plugin_hook_call_ */
 void plugin_hook_call_(struct lightningd *ld UNNEEDED, const struct plugin_hook *hook UNNEEDED,
-		       void *payload UNNEEDED, void *cb_arg UNNEEDED)
+		       tal_t *cb_arg UNNEEDED)
 { fprintf(stderr, "plugin_hook_call_ called!\n"); abort(); }
 /* Generated stub for subd_release_channel */
 void subd_release_channel(struct subd *owner UNNEEDED, void *channel UNNEEDED)

lightningd/test/run-jsonrpc.c

@@ -96,7 +96,7 @@ struct command_result *param_tok(struct command *cmd UNNEEDED, const char *name
 { fprintf(stderr, "param_tok called!\n"); abort(); }
 /* Generated stub for plugin_hook_call_ */
 void plugin_hook_call_(struct lightningd *ld UNNEEDED, const struct plugin_hook *hook UNNEEDED,
-		       void *payload UNNEEDED, void *cb_arg UNNEEDED)
+		       tal_t *cb_arg UNNEEDED)
 { fprintf(stderr, "plugin_hook_call_ called!\n"); abort(); }
 /* AUTOGENERATED MOCKS END */
 

wallet/test/run-wallet.c

@@ -547,7 +547,7 @@ void per_peer_state_set_fds(struct per_peer_state *pps UNNEEDED,
 { fprintf(stderr, "per_peer_state_set_fds called!\n"); abort(); }
 /* Generated stub for plugin_hook_call_ */
 void plugin_hook_call_(struct lightningd *ld UNNEEDED, const struct plugin_hook *hook UNNEEDED,
-		       void *payload UNNEEDED, void *cb_arg UNNEEDED)
+		       tal_t *cb_arg UNNEEDED)
 { fprintf(stderr, "plugin_hook_call_ called!\n"); abort(); }
 /* Generated stub for process_onionpacket */
 struct route_step *process_onionpacket(